A common operation in woodworking is the preparation of matched edge surfaces on two workpieces so they can be jointed together by gluing and/or other fastening means. For the maximum strength and best appearance, the mating surfaces of the two workpieces must align precisely without any gaps. A jointer-planer is routinely used by professional woodworkers to prepare such mating surfaces. A jointer-planer contains a rotating cutter head and two table surfaces whose elevations are slightly offset. The workpiece is lifted and then fed along the lower table toward the upper table where the rotating cutter head removes a portion of the workpiece, the thickness of which is equal to the difference in elevation between the two tables. Unfortunately, the jointer-planer is so large, cumbersome, and expensive that it is not feasible for the amateur woodworker to own or use one. Accordingly, it would be desirable for the amateur woodworker to have a tool which could perform the function of the jointer-planer, but at a fraction of its cost and size. More specifically, it would be desirable to have a matched edge jointer which could be used in conjunction with a router, a power tool owned by most amateur woodworkers.
Woodworking guides for use with a router are disclosed in Reneau, U.S. Pat. No. 4,840,209, issued Jun. 20, 1989, and in Cotton et al., U.S. Pat. No. 4,860,809, issued Aug. 29, 1989. The Reneau guide includes a rail member and a router trolley for making a precise cut on a workpiece. The Cotton et al. guide has two levels which enable mating cuts to be made on two workpieces with an alternating-contour-surface router bit. With both the Reneau and Cotton et al. guides, the router is used on the same side of the guide. Therefore, whatever deviation exists in the guide is doubled in the joint formed between the two workpieces. For example, assume the guide contains a uniformly curving concave bow of 0.05 inches (such a deviation from straightness inevitably occurs over time due to bending, warping, and so on). The two workpieces produced will each contain this same concave bow and the resulting joint will exhibit a gap of 0.10 inches at the center, large enough to be noticeable and to be unacceptable. Accordingly, neither guide is suitable for extended use in making precise matched edge surfaces.